Annealing process



Patented July 26', 1932 UNITED STATES PATENT OFFICE CHESTER S. HEATH, 01' SOUTH OEARIIESTON, WEST VIRGINIA, ASSIGNOB' TO ELEGTRO .IIETALLURQ-ICAL COMPANY, A CORPORATION OF WEST VIRGINIA ANNEALING PROCESS -11 0 Drawing.

My invention relates to softening or an- 5 of my invention is to provide a method for the annealing of various alloy compositions,

both ferrous and non-ferrous, which is par- "ticula'ily adapted to softening those ironchromium alloys which are softened by quenching. Another object is the shortening of time for the conduct of the annealing process and still another object is the production of a softer material than is obtainable by previous processes.

Broadly my invention consists in a heating of the alloy object to an elevated temperature, and a rapid quenching therefrom, repeating the cycle of heating and quenching a number of times in succession, the alloy being brought to substantially the same tem* perature in all the heating steps, and being quenched substantially at once upon obtaining the proper heat in each of said heating steps. believe I-am the first to discover that a greater annealing and softening is obtainable in an alloy of any kind, and particularly ina chrome-iron alloy, by a repeated heating and quenching of the material from an elevated temperature. 7

The following tests and experiments indicate the objects of my invention, the charfgcter of my process, and the results obtained yit. A well-known, corrosion-resistant, chro- 35 mium alloy, having the following composition, was used as material for demonstratin the effect of my process of the app'hcation o repeated cycles of heating and quenching I thereto. y Chromium 27.77 Carbon 0.25% Nickel 0. Silicon 0. 12% Manganese 0. 33% Remainder Iron Application fi lefl October '12, 1928. Serial No. 312,211.

This material was rolled to 20 gauge sheet, with care to conduct the rolling at a high temperature. The material was tested in the condition as rolled, and also after various heat treatments, including that of my new process, theresults indicated in the appended Aver- Number Expt H t of age No ea treatment samples Esrglehtreated value s... As rolled. 5 o. 20 3. Heated at 000 C. for 12 hrs. and quenched I in water 5 3. 25. 1 Heated 10 times to temperatures between 900 and 1000 C. and quenched in water .between successive beatings 5 3.

quenching at once in water, which series of.

operations may be conducted in an elapsed time of about an hour and a half for the 10 cycles, produces a still higher Erichsen value, showing a gain in softness and a very substantial saving in the time required for the annealing operation; That is to say, the total time required for the process of the invention is materially less than that required to secure the same degree of softening of like material by the old methods which consisted of a single quench preceded by a sustained heating of the material.

On another sample of commercial ironchromium alloy having high corrosion-resistance, and containing 25.4% of chromium, and 0.17% of carbon, the process of my mvention produced equally good results, as shown by the following table.

' Ulti- F 5 Expt Heat treatment mate E 70nd No. point strength 251013 11 area 1...--- AS Recd 68800 86250 23.5 47.2 2- do V 66800 86300 20.0 52.2 3.--- 850 C.-16 hrs. quenched in water-once 55900 77800 31.0 61.0 .10 12---- 850-900 (1-35 mins. A1-- ternately heated and quenched5times 50900 76300 320 69.3 5..-..- -900 C.-Altemately heated and quenched in water times 53600 78700 32.0 62.7 6.--" 800900 C.-Alternately heated and quenched in 15 watet times.--, 52150 75000 35.0 65.3

It may be noted from this table that substantial gains in softness, as indicated by the measurements of the elongation, and the reduction in area, are obtainable by the process of my invention and that the gains are progressive with increase in the number of cycles of heating and quenching through which the material is put- It may be noted that the temperature to, or above, which the material should be heated varies somewhat with the composition of the alloy. The desirable temperature will usually not be below 700 C. or 800 C. I find, however, that if the heating is conducted to a temperature between about 800 C. to 1000 C. a. sufficiently high temperature is obtained to be suitable for substantially all of the chromium containing alloys. It may be noted that in some cases it is undesirable to heat the materials to a temperature much above 1000 G. Since at a temperature of 1050 C.

to 1250 C. a rapid coarsening of the grainof some of the alloys occurs, which may detract from some of the desirable properties of the material. The above observations apply to the majority of the iron chromium alloys. When the process of my invention is applied to non-ferrous alloys, the desirable temperature may depart considerably from those above indicated, depending upon the character and compositionof the alloys treated.

' The process of my invention is applicable to other alloys than the simple chrome-iron alloys above discussed. It may be applied to alloys of other compositions, especially of those containing nickel, for the production of equally advantageous results. I find that. a chrome-nickel-iron alloy having the followmg composition is softened rapidly, easily and thoroughly by the same treatment.

Chromi 19.20% 0 Ni kP I 8.44% Silicon 0.43% Manganese 0.23% Carbon 0.14% Iron Remainder Samples of the above alloy were rolled to 20 gauge sheet, at a suitably elevated temperature, and specimens suitable for Erichsen test were cut from the rolled sheet. The

samples were heat treated as indicated in the following table with theindicated results.

Average Erichsen value sam- ples tested Asrolled Heated at 900 0. for 15 hrs, and quenched in water Heated 10 times between 900 and 1000 C.

and quenched in water Heated at 1050 C. for 1 hr. and quenched in water Heated 10 times to 1050 C. and quenched in water after each heating Heated at 1100 C. for 1 hr. and quenched in watet Heated 10 times at 1100 C. and quenched in water after each heating Heated at 1150 C. for 1 hr. and quenched in water. Heated 10 times to 1150" O. and quenched in water after each heating It may be noted that 10 cycles of heating to 900 C.,-and quenching at once in water, gives tained more conveniently. It is thus evident.

that this allo as well can be advantageously softened by t e process of my invention.

The process of my invention is not only. v

applicable to. those iron-chromium' alloys which are softened by quenching, but is also applicable to non-ferrous alloys. Alloys containing nickel, manganese. and copper have been found to have very valuable physical and electrical properties. Only a few however of the possible alloys of these three' materials are sufficiently ductile as cast to be workable in the cold. (The range of ductile alloys is shown by ternary diagrams by Pilling, Some electrical properties of copper-nickel manganese alloys, in the Transactions of the American Electrochemical Society, 1925.)

In order'to determine the effect of the proc-.

ess of my invention upon non-ferrous alloys. and particularly upon the alloys of this type which are found to be diflicult to .work, it was applied to an alloy having'the following com position: Y i

N1 Mn Cu This alloy is known to have valuable prop:

erties, but is found to be so difiicult to work that it is 1 unused. The alloy material wascast into one half inch square bars, and forged .at 900 G. into flat specimens having a thickness of of an inch, about A of an inch wide and three inches long. Various of these specimens were then given the treatments outlined in the following table:

Bend Fiber speci- Heat treatment elongamen tion- Per cent #10 As forged .9 #2.-" Heated for seven minutes 900 C. and water quenched 15 M--. Heated to 900 C. for 1 hour. Water quenched 19 #5.. Heated to 900 C. for 5 hours. Water quenched 17 #3.--. Alternately heated to 900 C. and water quenched 10 times 34 annealing process of my invention to this material results in a conspicuous gain in 'efiiciency of annealing.

By the process of my invention I am thus enabled to obtaina greater softness in various brittle alloys, both ferrous and non-ferrous, than is obtainable by other processes, and in many cases in a much shorter period of time than is required for other, less effective, annealing processes. My invention thus simplifies and cheapens the fabrication of articles made from such alloys and may make commercially usable certain alloys which are otherwise too brittle to be used.

While I have disclosed but a limited number of embodiments of my invention, it is capable of still other modifications therefrom without departure from the spirit thereof and it is desired therefore that only such limitations shall be imposed upon the appended claims as are stated therein or required by the prior art.

I claim as my invention:

1. The process of treating an alloy which is initially in a. hard state, and which alloy is adapted, by its composition, to be softened by bringing it to a high temperature'and then quenching it; which process comprises heating the alloy to and quenching it from a tem perature adapted to give substantially the maximum softening effect which can be obtained by a single quench; and then repeating the heating and quenching several times, the alloy being brought to substantially the same temperature in all the heating steps; the total time required for said process being material- 1 less than that required to secure the same egree of softening of like material by a single quench preceded by a sustained heating of said matenal at said temperature.

2. The process of treating an iron-chromiwhich can be obtained by a single quench; and

then repeating the heating and quenching.

several times, the alloy being brought to sub:

required to secure the same degree of softening of like material by a single quench pre ceded by a sustained heating of said material at said temperature.

3. The process of treating an alloy which is initially in a hard state, and which alloy is adapted, by its composition, to be softened by bringing it to a high temperature and then quenching it; which process comprises heating the alloy to and quenching it from'a temperature adapted to give the maximum softening effect which can be obtained by a single quench; and then repeating the heating and quenching several times, the alloy being brought to substantially the same temperature in all the heating steps, and the said alloy being quenched substantially at once upon obtaining the proper heat in each of said heating steps.

4:; The process of treating aniron-chromium alloy which is initially in a hard state, and which alloy is adapted, by its composition, to be softened by bringing it to a high temperature and then quenching it; which same temperature in all the heating steps, and I the said alloy being quenched substantially at once upon obtaining the proper heat in each of said heating steps.

5. The process of treating a nickel-manganese-copper alloy which is initially in ahard state, and which alloy is adapted, by its composition, to be softened by bringing it to a high temperature and then quenching it; which process comprises heating the alloy to and quenching it from a temperature adapted to give the maximum softening effect which can be obtained by a single quench; and then repeating the heating and quenching several times, the alloy being brought to substantially the same temperature in all of the heating steps;

the total time required for said process being materially less than that required to secure the same degree of softening of said alloy by a single quench preceded by. a sustained heating of said material at said temperature.

In testimony whereof, I aflix my signature.

Y CHESTER S. HEATH. 

